This invention relates to a workpiece assembling apparatus and a workpiece assembling method by which to locate a workpiece at a predetermined position, bring another workpiece set in place close to the workpiece, and fit the latter workpiece to the former workpiece, such as those for assembling a torque converter to a transmission in an automatic transmission.
An assembly operation for an automatic transmission of an automobile includes a step for assembling a torque converter to a transmission. FIG. 14 shows an outline of an ordinary transmission having a torque converter assembled thereto.
As shown in FIG. 14, an input shaft 13 is rotatably supported in a transmission case 12 of a transmission 11, and various speed change gears (not shown) are mounted on the input shaft 13. On one end side of the input shaft 13 in the transmission case 12 is mounted an oil pump 14, and a torque converter 16 is mounted in a converter housing 15 attached to the transmission case 12. The torque converter 16 is housed in a pump housing 18 having a boss portion 17. Thus, the driving force of an engine (not shown) is transmitted to the input shaft 13 via the torque converter 16 and a clutch and a planetary gear (not shown), and is then transmitted to a transfer shaft via the respective gears.
In such an assembling operation for the transmission 11, it has been customary practice that an operator withdraws the torque converter 16 inside a pallet, and assembles this torque converter 16 manually to the converter housing 15 of the transmission 11 on a conveyor.
In assembling the torque converter 16 to the transmission 11, their fitting portions must be fitted together in an appropriate manner. That is, five fitting portions, i.e., two splined fitting portions A, B, an oil pump fitting portion C, and oil seal fitting portions D, E, are present between the torque converter 16 and the input shaft 13. Thus, unless the respective fitting portions A, B. C, D and E are appropriately fitted even when the torque converter 16 is fitted over the input shaft 13 of the transmission 11, the torque converter 16 cannot be assembled to the transmission 11. In this respect, a conventional assembly operation for the torque converter 16 by an operator has been tiresome, and has taken time for positioning in fitting, resulting in a low work efficiency. Moreover, until the positioning for fitting is completed, the operator must hold the torque converter 16, shouldering. a heavy burden.
An apparatus for automatically assembling a torque converter to a transmission is disclosed, for instance, in Japanese Laid-Open Patent Publication No. 4-93130. A conventional "assembling apparatus" disclosed in this publication engages a torque converter from above with a transmission laid at a predetermined position. That is, the torque converter suspended from a suspension system is lowered toward the transmission by a lifting device to bring the engaging portions of these parts into contact. On this occasion, their engaging portions are lightly pressed against each other by an air cylinder. By rotating a rotating plate by means of a pulse motor, those engaging portions come into alignment, and become fitted. Under the urging force of the air cylinder, the torque converter descends to the transmission. This descent is detected by a detecting means of the rotating plate, issuing a rotation stop signal to the pulse motor, which stops the rotating plate. At the same time, a descent signal is outputted to the lifting device, lowering the suspension system, with the result that the torque converter is completely coupled to the transmission.
In the above-described conventional apparatus for assembling a torque converter to a transmission, the suspended torque converter is lowered by the lifting device, whereby the engaging shaft tube is contacted with the splined shaft of the transmission. With them being pressed against each other by the air cylinder, the rotating plate is rotated by the pulse motor, whereby their phases are brought into agreement, leading to their fitting.
Before the transmission is assembled, its splined shaft is usually free from engagement. When the engaging shaft tube of the torque converter is rotated while being pressed against the splined shaft of the transmission, the splined shaft also makes a rotation jointly with the engaging shaft tube owing to this pressure although the torque converter and the transmission are not engaged. This poses the problem that their phases do not easily agree, and no engagement is obtained.
With the conventional assembling apparatus, therefore, if the splined shaft of the transmission rotates together with the engaging shaft tube of the torque converter in an unengaged state, the torque converter must be lifted, and the same procedure performed again. Thus, assembly work becomes complicated, and requires a long time to complete.
Furthermore, the torque converter before assembly contains an oil for product testing. If the torque converter is suspended vertically by the lifting device, the inside remaining oil may leak, staining the transmission and the surrounding equipment.